<PAGE>

                                  EXHIBIT 31.2

                    CERTIFICATION OF CHIEF FINANCIAL OFFICER

I, Shanna L. Hanley, Treasurer, certify that:

1) I have reviewed this quarterly report on Form 10-Q of CNB Corporation;

2) Based on my knowledge, this quarterly report does not contain any untrue
statement of a material fact or omit to state a material fact necessary to make
the statements made, in light of the circumstances under which such statements
were made, not misleading with respect to the period covered by this quarterly
report;

3) Based on my knowledge, the financial statements, and other financial
information included in this quarterly report, fairly present in all material
respects the financial condition, results of operations and cash flows of the
registrant as of, and for, the periods presented in this quarterly report;

4) The registrant's other certifying officers and I are responsible for
establishing and maintaining disclosure controls and procedures (as defined in
Exchange Act Rules 13a-15(e) and 15d-15(e)) for the registrant we have:

      a)    designed such disclosure controls and procedures, or caused such
            disclosure controls and procedures to be designed under our
            supervision, to ensure that material information relating to the
            registrant, including its consolidated subsidiaries, is made known
            to us by others within those entities, particularly during the
            period in which this quarterly report is being prepared;

      b)    [intentionally omitted];

      c)    evaluated the effectiveness of the registrant's disclosure controls
            and procedures and presented in this quarterly report our
            conclusions about the effectiveness of the disclosure controls and
            procedures, as of the end of the period covered by this report based
            on such evaluation; and

      d)    disclosed in this report any change in the registrant's internal
            control over financial reporting that occurred during the
            registrant's most recent fiscal quarter(the registrant's fourth
            fiscal quarter in the case of an annual report) that has materially
            affected, or is reasonably likely to materially affect, the
            registrant's internal control over financial reporting; and

5) The registrant's other certifying officers and I have disclosed, based on our
most recent evaluation, to the registrant's auditors and the audit committee of
the registrant's board of directors (or persons performing the equivalent
function):

      e)    all significant deficiencies in the design or operation of internal
            controls which could adversely affect the registrant's ability to
            record, process, summarize and report financial data and have
            identified for the registrant's auditors any material weaknesses in
            internal controls; and

      f)    any fraud, whether or not material, that involves management or
            other employees who have a significant role in the registrant's
            internal controls; and

6) The registrant's other certifying officers and I have indicated in this
quarterly report whether or not there were significant changes in internal
controls or in other factors that could significantly affect internal controls
subsequent to the date of our most recent evaluation, including any corrective
actions with regard to significant deficiencies and material weaknesses.

Date: May 11, 2006

/s/ Shanna L. Hanley
-----------------------
Shanna L. Hanley
Treasurer